Light-emitting diode (LED) lighting typically uses nitridosilicate and oxonitridosilicate materials to enhance color rendering index (CRI) and chemical stability. WO Patent Application Publication No. 2006/061778 by Philips discloses an oxonitridosilicate phosphor of (Sr1−x−yCaxBay)2−zAlbSi12−bN16−bOa+b:Euz, which emits blue light. For white illumination applications, a second phosphor that emits red light, such as from yellow to red, is required. Furthermore, according to the formula of WO 2006/061778, the presence of oxygen is required when aluminum is present. In particular, nitridosilicates without oxygen have high condensed frameworks, and thus, have stable chemical structures and exhibit thermal stability.
Therefore, a nitride phosphor material having a proper emission spectrum and a method of making the same to enhance LED color shifting is needed to address various issues identified above.